The trophic interactions between herbivores and seaweeds have been scarcely studied for the Kongsfjorden ecosystem, despite the dominance of seaweeds in abundance and biomass in hard-bottom habitats. Knowledge on trophic seaweed-grazer interactions is necessary to comprehensively understand and ultimately model the structure of an Arctic food web. In recent years, data on seaweed consumption and indirectly on food preferences of herbivores were gathered. Moreover, observational and manipulative experiments were conducted in the field and laboratory, addressing the indirect effects between sea urchins and two seaweed species and how these affect behavioural urchin responses as well as community structure of hard-bottom habitats. This data could enter, for instance, a review on “marine food webs” listed on the tentative topic list for the workshop.